I have never used one to bring in a cow from a distance,I have brought in a yearling of either sex though.You can use one to approach a group of cows from a distance,make a few soft cow calls,break some branchs and advance very slowly at an odd angle,never directly,if you can keep some cover between urself and the cows you can get close enough for a shot with a bow.The lead cow is always the smartest of the herd and very spooky,so try to aproach from the rear and off to the side,if you hear the lead cow start to blow a loud alert call your busted and you probably have a very limited time left to take your shot so haste not!

I have done so just to prove it can be done. Now making calf calls in a distress tone will bring cows in that are very curious etc. However, you must not over use that call as elk are dumb like a fox.

If you use a calf call. You can call in a serrogate mother or lead cow. But have to do it right. I called in a calf I could of swore was a cat. Sounded just like a cat meowing constantly. I called it in 3 times after it seeing me. Cows will come to the calf call also. Have called in several using a calf call. Make sure you get close to use a calf call.
Is it a archery or rifle hunt?
Good luck and keep us posted.